If statements

[NanoBytes]

Hey, I am writing a compiler at the moment, and I could use the input of some experienced programers like yourselves.

I am working on how i want my if statements to work.

In C++ if statements follow this kind of rule

If the condition is not false then we will execute

And can be seen from

if (3) 
     cout << "This will work";
if (false)
     cout << "This will not work";

But I was also considering using a rule-set that follows

The condition MUST BE true to execute

And can be seen from

if (3) 
     cout << "This will NOT work";
if (true)
     cout << "This will work";

I was just wondering if either of these would be better on the user end of the language...

[LB]

You could enforce that the expression in the if statement must always evaluate to a boolean type without implicit casts ;)

[NanoBytes]

I wish it was that simple, but in my language I do not have a "bool" type. It only has two data types, the first being "number" (which is essentially a double in C++ terms), and "text" (which is similar to the std::string, but more functional).

(Remember that true/false are actually just the numbers 1 and 0)

Because my language does not have a bool type, look at this code:

main begin

    /////// THIS IS THE IMPORTANT LINE
    number X = true


    if X begin
        write("X = true")
    end
end

Now, because a "number variable" can hold any number I could have had line 4 be:
number X = -34.567

Now, that obviosly does not equal true, so should the if statement work? But, it also does not equal false.... I dont know what to do???

[Disch]

If you do not have a Boolean type, then what type do true and false evaluate to? Are they numbers?

If so, you could just say that if statements only evaluate if the provided number is = true (which I assume would be equal to 1)

So the user inputting this:

if X begin
    foobar
end

would be functionally identical to this:

if X = true begin
    foobar
end

The problem with that is that it'd be possible for X to be 'true' by mathematical computation, rather than being the result of a Boolean expression.

// assuming true == 1
X = 2
X -= 1

if X begin  // <- now this will work because X==1 which is ==true 

If you do not make a distinction between numerical and boolean types, this problem is unavoidable.